Robert bruce donaldson



(No Model.)

R. B. DONALDSON.

DENTAL INSTRUMENL No. 410,15 8.' Patented Sept. 3. 1889- 931 abbozm1 aUNITED STATES PATENT OFFICE.

ROBERT BRUCE DONALDSON, OF IVASHINGTON, DISTRICT OF COLUMBIA.

DENTAL INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 410,158, datedSeptember 3, 1889. Application filed May 24, 1889. Serial No. 311,925-(No model.)

To all whom it may concern:

Be it known that I, ROBERT BRUCE DONALD- SON, a citizen of the UnitedStates, residing at WVashington cit-y,in the District of Columbia, haveinvented certain new and useful Improvements in Dental Instruments; andI do declare the following to be a full, clear, and exact description ofthe invent-ion, such as will enable others skilled in the art to whichit appertains to make and use the same.

My invention relates tothat class of instruments employed in dentistryfor removing the pulp, or, as it is generally called, the nerve, andscraping and cleaning the pulp-canal in the root of a tooth. I

In a patent granted to me July 14, 1885, No. 322,265, is described andclaimed a dental instrument for removing the pulp and scraping the canalin the root of a tooth, which instrument, as well as all others of whichI am aware employed for this purpose, consisted of a straight, barbed,and tapered wire with a rigid handle. hen in use, these instruments arerotated or turned so as to cause the barbs at the point thereof toengage the pulp or nerve and hold the same, whereby the removal intactof said pulp may be ac complished. To introduce and rotaie suchinstruments-that is, those having rigid handles-has at times beendifficult of accomplishment, as when the cavity was at the back of thetooth. By bending the end of the instrument it could then be introducedinto the cavity, but the instrument could not be rotated when so bent,which movement of the instrument is necessary to secure the bestresults.

To overcome these objections as now found to exist in the practicaloperation of dental breaches employed to remove the pulp from thepulp-canal of a tooth and scrape said canal, especially in the posteriorteeth, is the object of my present invention, and to accomplish Whi 011I proceed as follows, reference being had to the accompanying drawings,forming a part hereof, for a better understanding of the details ofconstruction of the same, and in which drawings Figure l is a view inelevation of a dental instrument for removing the pulp from the canal ofa tooth and cleaning said canal, constructed according to my invention,the broaeh being shown as in its normal or straight position; and Fig. 2is a similar view of the inst-ruin cut, in partial section, illustratingthe broaeh as at an extreme angle for entering a cavity at the back of aposterior tooth.

The letterAdesignates a hollow handle, at the outer end of which issupported a bracket or arm B, and the inner end is screw-threadedorcarries a nut, as at (1-. Through this screwthread a of the rear endof the handle A prejects a thumb-screw O, that carries a set-nut c, andprojecting from the outer end of said handle is a shaft D, which shaftis of such length as to extend somewhat beyond and almost entirelythrough the handle and impinge against the end of the thumb-screw C, asshown in Fig. Upon this shaft is keyed a burr E, by which the same isrotated, and at the outer end thereof is a head or socket-piece d, thatreceives the broaeh F.

G is a box or journal-bearingfor the socketpiece (I, which bearing ispivoted or hinged to the outer end of the bracket B, as at g, and has aswinging movement upon said bracket. A portion, as at H, of the shaft ismade flexible, being preferably of spring-wire in spiral form, so thatthe shaft may be bent upon itself, as in Fig. 2,without affecting therotation thereof.

The operation of the device is as follows: To change the position of thebroaeh from a straight line, as in Fig. 1, to an angle, as in Fig. 2, sothat the instrument may be in proper position to readily enter and berotated in a cavity at the back of a tooth, the clamp-nut c is first rundown the screw 0, then by adj usting said screw 0 it is driven againstthe end of shaft D and said shaft forced outward. As the shaft movesoutward the flexible portion I-I thereof bends upward and causes thesocket d and broaeh held therein to assume an angle, as in Fig. 2. Anydesired degree of angularity may be given to the broaeh by manipulatingthe screw 0, and when the required angle has been reached the screw 0 isretained in posit-ion by the clamp-nut c. It will thus be seen that theinstrument may be readily introduced into cavities in the tooth,whatever the position of said cavities may be, and when so introducedinto a cavity a simple movement of the burr E by the forefinger andthumb of the operator will cause a rotation of the broaeh.

Instead of adjusting the shaft D by a screw I at its end, which screwenters the handle of the instrument and presses against the rear end ofthe shaft, as here shown, such shaft may be adjusted in any othersuitable manner, but the screw at the outer end of the handle, withset-nut, is the preferred construction. The portion H of the shaft mayalso be a light flexible wire cable, instead of a spiral wire, if suchcable will be found to accomplish the desired results.

The socket-piece or holder d may be of various forms and arranged toreceive broaches of different sizes.

Having thus described my invention, I claim as new and desire to securebyLetters Patent- 1. A dental instrument for removing the pulp andcleaning the canal in the root of a tooth, consisting of a hollowhandle, and a shaft held in said handle and adapted to be rotatedtherein and projected therefrom and carrying at its outer end thecleaning-tool.

2. A dental instrument of the nature described, composed of a handle,and a shaft held in said handle and adapted to be rotated therein andprojected therefrom, and having at its outer end the socket for holdingthe broach or cleaning-tool, which shaft has a flexible sectioninterposed in its length whereby the line of direction of said shaft maybe changed from straight to angular.

3. In a dental instrument of the nature de-' scribed, in combinationwith the handle, the bracket support or arm secured to said handle andcarrying at its out-er end the swinging bearing, and shaft held in saidhandle and swinging bearing, which shaft is adapted to be rotated insaid handle and bearing and to be projected from the handle, as and forthe purposes described.

4- In a dental instrument of the nature described, in combination,thehollow handle A, bracket support or arm B, with swinging bearing G, andshaft D, having flexible connection II, which shaft is held in saidhandle and adapted to be rotated therein and proj ected therefrom, andsocket or tool-holder d, substantially as described, for the purposesspecified.

5. In a dental instrument of the nature described, in combination, thehandle, shaft having the socket for the cleaning-tool at its outer endprojecting through said handle, and a thumb-screw arranged to projectthe shaft from the handle.

6. In a dental instrument of the nature described, in combination, thehollow handle with screw-threaded rear end, and shaft extending throughsaid handle, and a screw passing through said screw-threaded end ofhandle and impinging against the end of shaft, substantially asdescribed, for the purposes specified.

7. In a dental instrument of the nature de scribed, the shaft having thesocket for the cleaning-tool at its end, and burrs or thumbnut foroperating the same, and an interposed flexible portion whereby saidshaft may be rotated and bent at an angle.

8. In a dental instrument of the nature described, in combination, thehollow handle, the shaft with interposed flexible portion, the bracketwith swinging bearing for the shaft, the set-screw for projecting theshaft, and socket or tool-h0lder at the outer end of the shaft.

9. In a dental instrument of the nature described, in combination, thehandle, the flexible shaft carrying the cleaning-tool, the swingingbearing for the shaft, the burrs keyed thereon to operate the same, thescrew at the outer end of handle to project the shaft, and the set-nuton said screw, all constructed and arranged to operate substantially asdoseribed, for the purposes specified.

In testimony whereof I affix my signature in presence of two witnesses.

ROBERT ERUCE DONALDSON.

Vitnesses:

WM. I'I. BRERETON, H. J. LAUCK.

